Effects Of Different Aeration Conditions On Isochrysis Galbana (T-Iso) Ccmp 1324 In A Bench-Scale Photobioreactor

Abstract

The effects of superficial gas velocity (Ugr), gas entrance velocity (?), and bubble size on the growth of Isochrysis galbana (T-ISO) was investigated in 0.6 L photobioreactors operated with airlift pumps. Superficial gas velocities ranging from 7 to 93 mm s-1 were created using a 1.6 mm diameter syringe. Four sparger diameters were used to test the effects of sparger velocities that ranged from 2.48 to 73.4 m s-1. The effect of bubble size was evaluated by using two styles of air stones and an open glass pipet, which created a bubble size range of 0.5 to 5 mm. The kLa values for all experimental conditions were obtained. Cell growth increased linearly with increased superficial gas velocity and decreased with increased sparger velocity. Results indicate that smaller bubble size leads to some initial cell damage, but after time the increased gas transfer produces higher growth than larger bubbles. Two mechanisms were found to cause cell damage in I. galbana: increasing velocity at the sparger tip and reduced bubble size. The results show that airlift systems should be designed to mitigate hydrodynamic stress due to aeration. The implications for large-scale growth of microalgae in airlift-driven tubular reactors are discussed.